Reliability of Ships Hulls With Overall Residual Deformations

Abstract

Reliability of a vessel hull that has total deflection or kink is discussed in the paper. This hull defect may cause the sudden failure regardless of ship service life. There are no allowable values of characteristics (maximum deflection point) for this defect. There are no statistical data either, indicating the eventual increment of the deflection point, leading to the absence of the possibility to evaluate the hull reliability by this parameter. However, it is known that the presence of this defect causes the emergence of additional bending factor and the change of safety factor coefficient, influencing the allowable values of deck and bottom residual thickness. The residual thickness changes, depending on their operation time, are given in the rules of Russian River Register (RRR) and Russian Maritime Register of Shipping. Besides, these rules contain the allowable values of deck and bottom residual thickness. On the basis of the above, the dependencies for determining the possibility of failures emergence in terms of the average residual thickness of sheets in the link group due to the total deflection of the hull are offered. The condition according to which the average residual thickness of sheets in the links group is less than the allowable value established by the RRR Rules for a ship hull without common deformations is taken for a failure. The dependencies to calculate the decks' or bottoms' working area loss in the presence of deflection/kink given value are suggested. That allows calculating the amendment for permissible value of the average residual thickness of sheets. To evaluate the deformed hull reliability, the method of maximum deflection/ kink point determination plays an important role. The complexity of the task consists in the assignment of the residual deflection from the total one. A patent describing the residual deflected hull axis determination method, taking into account its curvature on the separate areas had been obtained by the authors of the paper. Based on this method, the dependencies to determine the maximum residual deflection/kink are offered. Thus, the opportunity to evaluate the reliability of the deformed hull depending on a given number of years of the vessel operation emerges.Keywords: reliability, allowable wear, residual total deflection/kink, the deviation of the normal to the surface from the vertical, curvature of the plot. For citation: Baryshnikov, Sergei O., Tatyana O. Karklina, and Valentin B.Chistov. "Reliability of ships hulls with over allresidual deformations." Vestnik Gosudarstvennogo universiteta morskogo i rechnogo flota imeni admirala S. O. Makarova 11.3 (2019): 519-533.Рассматривается надежность корпуса судна, имеющего общий прогиб или перегиб. Данный дефект корпуса может вызывать появление внезапного отказа независимо от продолжительности эксплуатации судна. Для этого дефекта отсутствуют допускаемые значения его основной характеристики (максимальной стрелки прогиба), а также отсутствуют статистические данные увеличения стрелки прогиба со временем, что...